Understanding How Soy Foods Impact Your Health

72 Comments

Hi Sweet Friends,

Oh, boy, we’re talking about soy. It’s a hotly debated topic these days, especially in the plant-based community. You’ve probably heard mixed reviews on this elusive bean — some good, some bad and some very ugly. I know it can be frustrating, but don’t throw your tempeh piccata in the trash just yet. With a little extra smarts, you can make an educated decision on how, why and if soy should be part of your diet. I certainly include it in mine, but that doesn’t mean I’ll be signing up for a soy-dog-eating contest anytime soon. As you’ll learn in today’s blog, organic, non-GMO soy foods can provide many benefits when eaten in moderation.

What types of soy foods are best, and how much should you eat?

In my fridge, you’ll find a variety of whole and minimally-processed soy foods, such as edamame, tempeh, miso and tofu. These foods land on my plate 2-3 times per week, although I tend to use tofu the least since it’s one of the more processed choices in my soy repertoire. They’re all rich in nutrients, antioxidants, protein, essential omega-3 fatty acids and phytoestrogens. A word to the wise, almost all soy is genetically modified. That’s why I always buy organic and search for the non-GMO label. It’s best to look for both stamps of approval, since organic does not guarantee 100% GMO-free food.

Eating soy as nature intended (or very close to it) can be beneficial to your well-being in a variety of ways. Soy protein and omega-3s are important for heart health. They also keep your arteries clear and cholesterol levels low. And contrary to some unsubstantiated fear-based claims, phytoestrogens may actually help reduce breast cancer risk among premenopausal women (more on soy and cancer in the following section). In addition, whole soy foods are easier to digest and taste better than their processed cousins. Plus, the microflora in fermented soy products, such as miso and tempeh, are your belly’s BFF.

Again, keep processed soy foods (and processed foods in general) to an absolute minimum. You’ll often find soy protein isolate or concentrate — both at the top of my list to avoid—on their ingredient lists. Faux chicken nuggets, soydogs and other fake meats not only contain processed soy, but a laundry list of food additives and preservatives as well. While these foods aren’t the devil, they certainly aren’t real, and therefore should never be a dietary staple. Think of them as an occasional novelty. The one exception I’ll mention is for those transitioning from a meat-heavy to a plant-happy diet. Eating faux meats and cheeses as a crutch can be helpful, but they definitely shouldn’t hold center stage for long.

We often cling to processed soy foods because of our culture’s protein paranoia. News flash sweet friends — protein doesn’t need to be the main event on your plate at every meal. Now I’m not saying that you don’t need protein, you absolutely do. But if you’re consistently eating a varied, plant-based diet, filled with beans, legumes, nuts, seeds, grains and vegetables, you’re in good shape! And with such an abundance of protein-rich choices in the plant family, are you starting to understand why soy is optional?

If you’re still concerned about protein, simply calculate your daily requirement using the following formula: Your body weight (pounds) multiplied by .36 equals the amount of protein (grams) needed for a moderately active adult. For example, a 140 pound person needs about 50 grams of protein per day. Here are just a few of the high-protein plant foods out there: one cup of lentils contains 18 grams of protein, one cup of quinoa contains 8 grams of protein and two tablespoons of almond butter contain 7 grams of protein. See how easy it can be to meet your protein needs?

Soy seems pretty straightforward when you’re talking about quality and quantity, but the conversation gets trickier when you begin to explore the claims flying around about soy and certain health issues. Next up, soy dangers demystified!

Is there really a link between soy and cancer?

You may have heard that eating soy increases your risk of cancers such as prostate and breast cancer, but the opposite may be more likely. Recent research has shown that lung cancer patients with a history of eating soy have a better survival rate than those who have eaten less or no soy in the past. Men who consume soy have actually been found to have a reduced risk of prostate cancer. And then there’s the most frequently misunderstood relationship — soy and boobs.

When a woman regularly eats protein-rich and phytoestrogen-rich soy foods, studies show that her breast cancer risk drops. Soy’s potentially protective role may be due to its isoflavones which are phytoestrogens (literally meaning “plant estrogens”) and may block some of estrogen’s activity. It could also be the result of various anti-cancer phytochemicals in soybeans. To get the maximum benefit of soy’s protection, some studies show that healthy soy foods should be part of the diet during puberty and adolescence when breast tissue is forming. But that doesn’t mean that you should go soy-crazy. As we’ve discussed, quality and quantity matter. For example, the ladies who participated in the original studies connecting Asian women’s lower breast cancer risk to their regular soy consumption were eating small, moderate amounts of whole or minimally processed soy foods (not buckets of soy jerky!).

So why are people still concerned about soy when it comes to estrogen-sensitive diseases like breast cancer? We’re still not sure how much soy is safe for individuals such as breast cancer patients and survivors, so doctors often recommend that their patients play it safe by avoiding soy completely. This is a very common approach because hormone-sensitive cancer receptors are stimulated by human estrogen and the structure of soy is similar to human estrogen. At the same time, eating soy foods can actually be beneficial to these types of patients and often recommended to patients in moderation during hormone blocking treatment. And it’s also important to mention that soy supplements (not soy foods) are frequently used in the animal studies that point an accusatory finger at soy and cause alarm.

In Life Over Cancer, Keith Block, Oncologist MD, states that based on his review of the current research, “both premenopausal and postmenopausal women with ER+ tumors can safely eat soy foods such as tempeh and tofu about two or three times per week.” Interestingly enough, many of the same doctors who tell patients to avoid soy altogether never mention the abundant amounts of estrogen and other growth hormones found in meat and dairy products! So if you’re avoiding soy as a result of a cancer diagnosis, think twice about animal products as well.

What about soy-loving fellas?

Good news for boys and men! Despite the buzz that “girlie” phytoestrogens may have a negative effect on hormones and fertility for males, there isn’t a single study showing this—nothing linking these issues to soy formula for baby boys or tofu burgers for boy scouts—nada. In fact, a huge study published in 2009 showed that soy food consumption actually reduced prostate cancer risk by 26 percent among soy-strong men. If you’re pregnant and concerned about soy affecting your baby boy, remember that any studies on the subject have involved animals consuming “large” or “high” amounts of soy—not something that fits into our model of eating a moderate amount of unprocessed, whole soy foods.

If you’re concerned about male reproductive issues, it might be time to look more closely at your dairy consumption. A recent study found that consuming high-fat dairy products like cheese and sour cream may lower sperm quality and fertility, perhaps due to the naturally occurring reproductive hormone, pesticides, chlorinated pollutants and/or heavy metals present in dairy foods.

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Does soy impact thyroid health?

Another soy misunderstanding: Much like the confusion surrounding cruciferous veggies and thyroid function, soy isoflavones do not cause hypothyroidism or exacerbate hypothyroidism. Research published in the Journal of Clinical Endocrinology and Metabolism studied two groups of women: one group with 2 mg of phytoestrogens (plant estrogens in soy) and one group with 16 mg of phytoestrogens. They found a small percentage of the high-soy intake group had some decrease in thyroid function, but it should also be noted that the high-soy intake group also saw significant health benefits from this increased soy consumption, such as decreased insulin resistance, decreased inflammation markers and lower blood pressure.

You should be aware that soy isoflavones may absorb some of the iodine needed to make thyroid hormones, which could increase the body’s need for iodine. But, as long as iodine intake is sufficient, soy shouldn’t be a problem for the thyroid. Iodine is especially high in sea veggies, which means that miso soup with tofu cubes and wakame seaweed is not only a soothing combo, but also a match made in thyroid health heaven.

Please note that soy foods may affect the absorption of meds used to treat hypothyroidism. If you take medicine to treat hypothyroidism and love soy, check with your doctor so that your dosages can be adjusted accordingly. And still eat seaweed — it’s good for you!

If soy isn’t a great fit for me, what are the best alternatives?

While soy can be a convenient and healthy part of your diet, know that if you’re allergic (soy allergies are quite common), feel congested after eating it or need to avoid soy for other reasons, it’s not an essential part of a plant-based diet and can be eliminated without compromising your health. As I mentioned earlier, plant protein and essential fatty acids are found in a variety of beans, lentils, nuts, seeds, quinoa and whole grains. And soy-free milk, cheese and meat alternatives are widely available today. Be a label detective and choose products with a short list of ingredients you can pronounce. I opt for a variety of nut, seed and grain-based alternatives, such as almond milk, hemp milk, flax milk, nut cheese and grain meat.

For more soy schooling, check out these highly researched and credible resources:

Whether or not you decide to include soy in your diet is very personal decision that only you can make, but hopefully you feel much more prepared to make that choice with this knowledge under your belt.

72 Responses…

Awesome! Thank you. I was JUST thinking about this. I’ve seen a lot of negative press about soy lately. I don’t eat a lot of it but I was wondering if it would be best to cut it out all together. This helps immensely.

Also – I just moved to Europe. I’m confused about the GMO laws here, which I know are tighter (thankfully!). I believe that if something has GMO in it then it must be labled as such, correct? If it doesn’t say it has GMO crops in it am I safe to assume it is GMO free? Does anyone know?

Hi aimee,
I don’t know about the rest of Europe in the UK we have all GMO food labelled. In Tesco supermarket, all their own-brand food is GMO free. We’re not keen on GMO here in the UK, and thankfully our stores listen to the public!

Foods containing GMO products do not need to be marked as such in the US. There have recently been attempts at passing legislation to accomplish this, but they have failed. As of now, you can safely assume that anything that is not marked “organic” has the possibility of have GMO products in it: especially corn and soy as these are the most prevalent GMO products…

This is helpful, Kris. The soy issue is confusing. I am not sure soy affects me well, but I’m going to reconsider. I entirely agree with you about avoiding processed and GMO soy. Love your blog and your leadership on dietary issues and health!

Though soy, in its original state, is an incredibly high phytonutrient food, it is high histamine and therefore may cause rashes, bloating, migraines, severe inflammation and other allergy-like symptoms, especially in people who have histamine intolerance, mast cell activation and mastocytosis (but also in people who don’t). Obviously histamine induced inflammation is something you definitely don’t want to deal with in cancer as it can promote tumor growth (interestingly there are a number of studies looking into antihistamines shrinking tumors).

As one of the quickest rising allergies in the world (likely because many of us lack the enzyme/s to digest it), it’s often the first thing I suggest people look at when they tell me they have weird allergy symptoms, with a negative IgE or RAST test.

Eating only fermented soy gets rid of the problems associated with the anti nutrients in soy – and in other pulses as well. Fermented soy is pretty easy to find, although natto is a bit of an acquired taste. Tamari, tempeh and miso are all great fermented products. For other pulses, just sprouting them cuts the phytic acid by about half and boosts the nutritional value – just takes a bit of planning ahead.

But hardly anyone is going to be suffering from a shortage of protein as long as they’re eating nutrient dense foods, with or without soy. We know that over a long history, Asian cultures that traditionally have consumed quite a bit of soy tend to be long-lived, and for me that’s more convincing than conflicting study results. So for me, I include fermented soy because it adds variety and I do quite a bit of Asian fusion food. I rarely eat non-fermented soy, and absolutely never non organic – if it isn’t organic you are pretty much guaranteed to be consuming a GMO food. Don’t do that.

This blog post is RICH with priceless information on soy: wow! I had wanted clarification about soy for a loooooooong time and having read so many different (conflicting) information, it was getting very confusing.

Great article!
I used to eat only organic local soy from a small farmer (http://www.vermontsoy.com/).
I’m so afraid that Monsanto has gotten its dirty claws into most soy out there, but I felt comfortable with Vermont Soy after meeting the farmers and talking to them about my concerns.

Recently I had a food sensitivities test done, and soy came up with LOTS of reaction! So…I avoid it now. Gosh, it’s in almost all packaged food!!!!!!!

I am a breast cancer survivor who was treated at Memorial Sloan Kettering and was told similar information to as what Kris has written. I am hoping this link to their nutrition pamphlet on healthy eating for breast cancer will work. If so, scroll to page 26 on soy.

One thing they emphasize, which I also saw on Dr. Oz, is to avoid SOY PROTEIN ISOLATE, a highly processed version particularly harmful for estrogen-based cancers, and which lives sneakily in all kinds of unexpected places like crackers and energy bars. Here is the link to Dr. Oz:

This blog post is RICH with amazing information I absolutely needed. I’ve been reading so many contradictory information I was a little confused quite frankly.

I love my edamame and I’m determined to find a recipe that’ll make tofu taste good (Yottan Ottenlenghi has a great recipe in his new book and I love yours in CSKitchen!) so your clear guidelines Kris and abundance resources above are really helpful.

I rarely use soy products now because of the Cornucopia report about hexane gas extraction, and when I do buy tofu, I buy organic, fermented tofu. I also consult Cornucopia’s list of brand names that use or don’t use hexane gas extraction before buying a soy-based product.

Hi Glowy, thanks for the soy talk. I still am a little confused about it. There is a German food chemist named Udo Pollmer he is reporting that soy as such is poisoness and that it is weakening the immuno system. Unfortunately his Youtube things are in german. But he says that the benefits of soy are made up marketing tricks starting in the 50´s and he states that when you are trying to look up the studies for the health benefits on soy you actually find no study… This is all very confusing. Does anyone know something about it?

Thanks for a great article. As a nutritionist, I see lots of women actually gain weight when they increase their soy consumption – even the whole, organic forms. I’ve also seen many women’s hormone levels change, confirmed through saliva analyses – and not for the better. I think the safest soy is fermented and organic, period. Also, there is definitely truth to the harmful effects of conventionally raised meat and the hormones they contain, however, grass-fed meat (for those who eat meat) from local, humanely-raised and happy animals, is actually anti-inflammatory and contains anti-cancer compounds that have been well researched. There needs to be more discussion and openness from vegans and vegetarians to that truth, even if they decide to abstain themselves.

I agree Veronica. I am a nutritionist too and like you, see a lot of women gain fat or fail to loose it when they are eating a lot of beans and lentils. Yes, for vegans and vegetarians there are plenty of protein sources and you definitely can get enough, but often then there is too high a consumption of carbohydrates, even if they are from whole food sources. Bottom line, fermented soy can be very helpful in fulfilling your protein requirements, but let’s all keep an eye on making sure we are not getting too many carbs, even from whole foods.

Thanks Kris! I get asked by a lot of friends transitioning to a plant-based diet about tofu recipes — it’s important to know how many protein alternatives there are since, like you said, soy should be eaten in moderation.

That said, I also know friends and family who avoid soy at all costs. I hope your article helps demystify some of the effects of soy.

I’m still unclear about the safety of whole soy foods during pregnancy. I’ve heard it can negatively affect a male fetus, but I’m not sure how much soy one would have to eat for it to be considered unsafe.

Unless one is in menopause, soy should be avoided EXCEPT in the fermented form (and then only organic of course!) “The Whole Soy Story” is a highly recommended read on the science as well as the businesses behind soy.

1. High Phytic Acid (Phytates): Reduces assimilation of calcium, magnesium, copper, iron and zinc. Phytic acid in soy is not neutralized by ordinary preparation methods such as soaking, sprouting and long, slow cooking, but only with long fermentation. High-phytate diets have caused growth problems in children.

Mercola is not a credible source. The same website continues to claim a link between vaccines and autism. This article, however, is very comprehensive and weighs the pros and cons very well. Great read!

Thanks for your fresh and clear approach. Interesting to learn that it’s soy supplements used in testing as opposed to food – definitely great info to look for when I read about studies citing ‘dangers of soy’.

I like to treat soy mostly as a condiment, and will eat organic tofu maybe once a month or so. Usually at a restaurant when that’s their veggie option. It’s super-easy and soft finger food for the kids, and they love it too!

Just to let you know, women with estrogen receptive characteristics to breast cancer cells are advised NOT to eat soy products. ER positive cells feed on estrogen, and soy apparently looks, to an ER positive cancer cell, like estrogen.

My concern with soy has been re: my thyroid (I have been diagnosed with Hashimoto’s). Despite avoiding both soy, raw cruciferous veggies and almost all gluten, my TSH continues to increase toward hypothyroidism so I will likely begin taking armour thyroid in the near future.

I will follow-up with the concern re: adequate iodine and possible interactions between soy and armour, but am interested in reading more about the misunderstanding re: cruiciferous/goisterous veggies. My green juices are pretty much limited to romaine these days :/ Any suggestions on where I can read more about this topic??

Iodine will increase your TSH levels and lead to increased thyroid gland (I.e. goiter). Research Nature thyroid. Results have been better than Armour and are not synthetic. Not sure where you live, but seek out doctor who specializes in thyroid dysfunction (not same thing as endocrinologist).

Tanya, I just wanted to let you know that in December of 2012 I was diagnosed with Hypothyroidism due to Hoshimoto’s disease. I am on synthroid and have been now for 8 months. I also have a cancer size goiter and several nodules on my thyroid. I spoke with my Doctor about letting me try diet to aleviate issues before we considered surgery. He agreed. I have to go in every 2 months for ultra sounds and blood work, but since I found Kris’s book and her website, I went TRUE VEGAN cold turkey (so to speak). I ignored all the crusiferous veggie info I heard and I juice with whatever I want, I eat spinich, broccoli and Kale, all of it. I DO NOT EAT SOY. That is a different story, but just wanted you to know that though my goiter and nodules have not shrunk they have not grown either. Also they have been lowering my thyroid mcg’s amount every time I go in. My Dr is surprised and is letting me stay with a Vegan diet and see how I do for a full year with 2 month checkups. If all is well, then I won’t have to have surgery and I can just monitor it. I won’t let them test if it is cancer for sure, again a different story, but so far they and I are pleased with my results. I do also supplement with Vit B12 and Kelp. So my advice to you is don’t quite the veggies, they are awesome for your body and thyroid and see if it makes a difference. Since I went Vegan, I sleep better and I have more energy. I hope this helps you a bit.

I have read that Soy really is hard on our systems and further that it slows our metabolism. If you read the book Fast Metabolism, the author talks about making people into wrecks by overfeeding them soy. In her case it’s just straight Tofu she is giving them: breakfast lunch and dinner. She has done this for actors preparing for roles at her retreat centers in Colorado. She says she gets results making them appear to age 10 years and gain 10 pounds on the soy regimen. So I have given up soy.

I think you overlooked your own comment. Yes, the overfeeding of soy is not a good thing. The overfeeding of any food is not a good thing. Her article is not advocating overfeeding. I hardly think 2-3 times a week is overfeeding. I think her article is advocating that you make a educated choice and do what is right for you and your body.

Soooooo SOY !!!! Still not totally convinced, but I don’t think anyone can truly say if it is ok or not. I also do not eat any non organic soy, except for soy sauce. I have been concerned over Sprouted Soy in Ezekel Bread. I read sprouted soy is even worse for you. I feel like you can’t get a real lay of the land on soy cause everyone seems to have a vested interest.

Thank you so much for this detailed break-down on soy Kris Carr! I share most of this information with my clients and friends ALL THE TIME! There is so much mis-information and this guide is extremely helpful and a “gem” to share! You continue to be a great resource to coaches such as myself and to the general public on all things related to plant-based and spiritual health. Jai Bhagwan.

Yes, soy and I have had quite a roller coaster ride since I adopted a plant-based diet last March. At first, I had to face my inhibitions about tofu, then articles linking such things to breast cancer shut that avenue down quick. Then edamame happily shot to the top of the list, but then the GMO issue really left a bad taste in my mouth and I started filtering out all non-organic food with soy. Some new organic markets have opened up near my home, so I’m happy to be able to bring edamame back into the mix! Thanks for the great article, Kris. You really have a way of bringing clarity to complex issues. <3

Thanks for all the soy info! I have been very confused by all the conflicting thoughts about soy’s safety. I feel reassured that my whole soy choices are a good idea after all. I have a question about soy and dairy milk alternatives, however. I generally choose almond milk, but I have noticed that most of it is made with carageenan, which I have heard can cause stomach cancer. What are your thoughts on carageenan?
Thanks!
~jen

I was allergy-tested a few months ago and tested positive for a soy allergy with the skin test but not in the blood test. I have no idea what this means or whether I can or cannot consume soy then. It’s safest, I suppose, to not but … it’s tough for a vegan gal to avoid, esPEcially when visiting a vegan restaurant, speaking of tempeh seitan, Kris, lol. The alternative is seitan which is gluten so … pick your problem! Famous docs like Alejandro Junger and Frank Lipman recommend against soy ~ and gluten too, btw ~ so, as you said … have to make your own decision and then (try to) feel good about it.

This article dealing with the never-ending soy controversy is excellent! It’s not as confusing as people make it out to be; however, there has been so much damage done to soy’s reputation (even the whole forms of soy such as tempeh, edamame, and tofu) that I fear it is irreparable. I also find it interesting that doctors tell their patients to cut out soy, but not animal protein. Good point!

This is a mostly well done article. I like that someone is speaking against all the faux meats. If you want to be a vegetarian, then eat vegetables, not something in the form of meat, and meant to taste like meat. Embrace your decision!! I do think you should be qualifying your comments about dairy and meat… not all dairy and meat are the same, and if one chooses to consume pasture raised organic meats, they are very healthy compared to their CAFO distant relatives. (IMHO, unless you are consuming pastures based, raw dairy, it should should be mostly avoided. Pasteurization kills off much of what is good about it.) Also, I feel like there should have been a bit of discussion about varying the protein sources while on a vegetarian diet… so that you get a complete array of proteins in the diet.

Thanks for the article, very interesting. It doesn’t really mention soy milk, is that considered ok or is it highly processed too? My daughter is anaphylactic to dairy, so was put on soy formula at 8 months, and now drinks soy milk (she’s 3). I’ve always worried about it, but the dietician, allergist and paed all said it was fine. I discourage her from drinking much of it, and I buy one that says non-GMO. What do you think?

Finally a great article & update about soy! Just like everything, enjoy in moderation. Thank you for reminding us that organic does not mean GMO-free. Soy is a HUGE Monsanto product & GMO’s should be avoided wherever possible!

An important large study published last year analyzed the results of three population studies (2 US/ 1 Chinese) on breast cancer patients, each of which showed that soy isoflavone intake was associated with reduced risk of breast cancer recurrence and/or mortality.

The 2012 analysis found that soy isoflavone intake of more than 10 mg/ day was associated with decreased risk of recurrence.

Thank you for your soy article….as always a very confusing topic though i think you have clarified the confusion: don’t eat processed or GMO soya beans and eat in moderation.
You have not mentioned soya milk , i drink Bonsoy, (not sure if it is available outside of Australia)which uses whole organic beans, tapioca syrup, job’s tears and calcium carbonate. I try ot moderate it, but it is soooo yummy, especially in chai…is soya milk considered too processed to drink?????

As a holistic nutritionist (including Certified Vegetarian Nutritionist) I am a great fan of whole organic soy foods including organic tofu. It has been made for centuries in the kitchens of Japanese and Chinese women so it technically is not highly processed although more processed than tempeh and miso.

The deadly soy found in protein powders, soy baby formula’s and fake cheese and fake meat needs to be avoided. Any isolated or concentrated protein powder (soy, whey, hemp, rice, pea) is always a source of MSG. Check out http://www.truthinlabeling.org for more information. When these proteins are processed the amino acids often reformulate into a neurotransmitter (MSG.) a virus or a hormone. They are also difficult to digest and cause digestive disorders and eliminative tract disorders including cancer of the digestive tract. There is a Proctologist in our city that says these protein powders keep him in business because they destroy the digestive system. Isolated and concentrated soy is processed in aluminum vats using acid and alcohol washes, infusing the final product with high levels of aluminum (remember the baby formula?) As a vegan, I have more than adequate protein from my whole food plant based diet. Eat real food!

Hi. I have really been enspired by your love for life. It has been a mazing journey for you. I’ve startedy journey eat a plant based diet and I’m a maze how are body function really well. I think I was borned to be a vegetarian but it is hard when your husband wants meat at almost all meals. I was going to start your green juices but was wondering what you think of this juicers for starters. HUROM PREMIUM VERTICAL COLD PRESS JUICER – HU500
Thanks,
Judy

Hi Kris and all,
I’ve found conflicting info. on the average amount of protein humans (and even dogs) need.
I saw somewhere the equation .39 per pd.? I also read 50-70 grams a day. Is there an easy way to understand this and also to explain it, with studies to back it up?
With gratitude,
Sheri

I have been confused on the talk about the negative effects of soy. i read the book The Okinawa Program and they have the highest number of centurians who are healthy and they also have some of the lowest rates of camcer but they eat soy. So i don”t understand the difference?